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Oliver Hartkoppa1044e32010-12-02 10:57:59 +00001/*
2 * slcan.c - serial line CAN interface driver (using tty line discipline)
3 *
Paul Gortmaker3396c782012-01-27 13:36:01 +00004 * This file is derived from linux/drivers/net/slip/slip.c
Oliver Hartkoppa1044e32010-12-02 10:57:59 +00005 *
6 * slip.c Authors : Laurence Culhane <loz@holmes.demon.co.uk>
7 * Fred N. van Kempen <waltje@uwalt.nl.mugnet.org>
8 * slcan.c Author : Oliver Hartkopp <socketcan@hartkopp.net>
9 *
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by the
12 * Free Software Foundation; either version 2 of the License, or (at your
13 * option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful, but
16 * WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License along
Jeff Kirsher05780d92013-12-06 06:28:45 -080021 * with this program; if not, see http://www.gnu.org/licenses/gpl.html
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000022 *
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
26 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
27 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
29 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
33 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
34 * DAMAGE.
35 *
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000036 */
37
38#include <linux/module.h>
39#include <linux/moduleparam.h>
40
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000041#include <linux/uaccess.h>
42#include <linux/bitops.h>
43#include <linux/string.h>
44#include <linux/tty.h>
45#include <linux/errno.h>
46#include <linux/netdevice.h>
47#include <linux/skbuff.h>
48#include <linux/rtnetlink.h>
49#include <linux/if_arp.h>
50#include <linux/if_ether.h>
David S. Miller84b3cdc2010-12-08 18:41:03 -080051#include <linux/sched.h>
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000052#include <linux/delay.h>
53#include <linux/init.h>
Andy Shevchenko81fc70d2011-07-17 22:26:37 +000054#include <linux/kernel.h>
Tyler Halla8e83b12014-06-15 22:23:17 -040055#include <linux/workqueue.h>
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000056#include <linux/can.h>
Oliver Hartkopp156c2bb2013-01-17 18:43:39 +010057#include <linux/can/skb.h>
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000058
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000059MODULE_ALIAS_LDISC(N_SLCAN);
60MODULE_DESCRIPTION("serial line CAN interface");
61MODULE_LICENSE("GPL");
62MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
63
64#define SLCAN_MAGIC 0x53CA
65
66static int maxdev = 10; /* MAX number of SLCAN channels;
67 This can be overridden with
68 insmod slcan.ko maxdev=nnn */
69module_param(maxdev, int, 0);
70MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
71
72/* maximum rx buffer len: extended CAN frame with timestamp */
73#define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
74
Andre Naujoks87397fe2013-09-13 19:37:13 +020075#define SLC_CMD_LEN 1
76#define SLC_SFF_ID_LEN 3
77#define SLC_EFF_ID_LEN 8
78
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000079struct slcan {
80 int magic;
81
82 /* Various fields. */
83 struct tty_struct *tty; /* ptr to TTY structure */
84 struct net_device *dev; /* easy for intr handling */
85 spinlock_t lock;
Tyler Halla8e83b12014-06-15 22:23:17 -040086 struct work_struct tx_work; /* Flushes transmit buffer */
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000087
88 /* These are pointers to the malloc()ed frame buffers. */
89 unsigned char rbuff[SLC_MTU]; /* receiver buffer */
90 int rcount; /* received chars counter */
91 unsigned char xbuff[SLC_MTU]; /* transmitter buffer */
92 unsigned char *xhead; /* pointer to next XMIT byte */
93 int xleft; /* bytes left in XMIT queue */
94
95 unsigned long flags; /* Flag values/ mode etc */
96#define SLF_INUSE 0 /* Channel in use */
97#define SLF_ERROR 1 /* Parity, etc. error */
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000098};
99
100static struct net_device **slcan_devs;
101
102 /************************************************************************
103 * SLCAN ENCAPSULATION FORMAT *
104 ************************************************************************/
105
106/*
107 * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended
108 * frame format) a data length code (can_dlc) which can be from 0 to 8
109 * and up to <can_dlc> data bytes as payload.
110 * Additionally a CAN frame may become a remote transmission frame if the
111 * RTR-bit is set. This causes another ECU to send a CAN frame with the
112 * given can_id.
113 *
114 * The SLCAN ASCII representation of these different frame types is:
115 * <type> <id> <dlc> <data>*
116 *
117 * Extended frames (29 bit) are defined by capital characters in the type.
118 * RTR frames are defined as 'r' types - normal frames have 't' type:
119 * t => 11 bit data frame
120 * r => 11 bit RTR frame
121 * T => 29 bit data frame
122 * R => 29 bit RTR frame
123 *
124 * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64).
125 * The <dlc> is a one byte ASCII number ('0' - '8')
126 * The <data> section has at much ASCII Hex bytes as defined by the <dlc>
127 *
128 * Examples:
129 *
130 * t1230 : can_id 0x123, can_dlc 0, no data
131 * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33
132 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55
133 * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request
134 *
135 */
136
137 /************************************************************************
138 * STANDARD SLCAN DECAPSULATION *
139 ************************************************************************/
140
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000141/* Send one completely decapsulated can_frame to the network layer */
142static void slc_bump(struct slcan *sl)
143{
144 struct sk_buff *skb;
145 struct can_frame cf;
Andre Naujoks87397fe2013-09-13 19:37:13 +0200146 int i, tmp;
147 u32 tmpid;
148 char *cmd = sl->rbuff;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000149
Andre Naujoks87397fe2013-09-13 19:37:13 +0200150 cf.can_id = 0;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000151
Andre Naujoks87397fe2013-09-13 19:37:13 +0200152 switch (*cmd) {
153 case 'r':
154 cf.can_id = CAN_RTR_FLAG;
155 /* fallthrough */
156 case 't':
157 /* store dlc ASCII value and terminate SFF CAN ID string */
158 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN];
159 sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN] = 0;
160 /* point to payload data behind the dlc */
161 cmd += SLC_CMD_LEN + SLC_SFF_ID_LEN + 1;
162 break;
163 case 'R':
164 cf.can_id = CAN_RTR_FLAG;
165 /* fallthrough */
166 case 'T':
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000167 cf.can_id |= CAN_EFF_FLAG;
Andre Naujoks87397fe2013-09-13 19:37:13 +0200168 /* store dlc ASCII value and terminate EFF CAN ID string */
169 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN];
170 sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN] = 0;
171 /* point to payload data behind the dlc */
172 cmd += SLC_CMD_LEN + SLC_EFF_ID_LEN + 1;
173 break;
174 default:
175 return;
176 }
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000177
Andre Naujoks87397fe2013-09-13 19:37:13 +0200178 if (kstrtou32(sl->rbuff + SLC_CMD_LEN, 16, &tmpid))
179 return;
180
181 cf.can_id |= tmpid;
182
183 /* get can_dlc from sanitized ASCII value */
184 if (cf.can_dlc >= '0' && cf.can_dlc < '9')
185 cf.can_dlc -= '0';
186 else
187 return;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000188
189 *(u64 *) (&cf.data) = 0; /* clear payload */
190
Andre Naujoks87397fe2013-09-13 19:37:13 +0200191 /* RTR frames may have a dlc > 0 but they never have any data bytes */
192 if (!(cf.can_id & CAN_RTR_FLAG)) {
193 for (i = 0; i < cf.can_dlc; i++) {
194 tmp = hex_to_bin(*cmd++);
195 if (tmp < 0)
196 return;
197 cf.data[i] = (tmp << 4);
198 tmp = hex_to_bin(*cmd++);
199 if (tmp < 0)
200 return;
201 cf.data[i] |= tmp;
202 }
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000203 }
204
Oliver Hartkopp156c2bb2013-01-17 18:43:39 +0100205 skb = dev_alloc_skb(sizeof(struct can_frame) +
206 sizeof(struct can_skb_priv));
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000207 if (!skb)
208 return;
209
210 skb->dev = sl->dev;
211 skb->protocol = htons(ETH_P_CAN);
212 skb->pkt_type = PACKET_BROADCAST;
213 skb->ip_summed = CHECKSUM_UNNECESSARY;
Oliver Hartkopp156c2bb2013-01-17 18:43:39 +0100214
Oliver Hartkopp2bf34402013-01-28 08:33:33 +0000215 can_skb_reserve(skb);
216 can_skb_prv(skb)->ifindex = sl->dev->ifindex;
Oliver Hartkoppd3b58c42015-06-26 11:58:19 +0200217 can_skb_prv(skb)->skbcnt = 0;
Oliver Hartkopp156c2bb2013-01-17 18:43:39 +0100218
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000219 memcpy(skb_put(skb, sizeof(struct can_frame)),
220 &cf, sizeof(struct can_frame));
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000221
222 sl->dev->stats.rx_packets++;
223 sl->dev->stats.rx_bytes += cf.can_dlc;
Marc Kleine-Buddea2e78cf2015-07-11 21:16:08 +0200224 netif_rx_ni(skb);
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000225}
226
227/* parse tty input stream */
228static void slcan_unesc(struct slcan *sl, unsigned char s)
229{
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000230 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
231 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
232 (sl->rcount > 4)) {
233 slc_bump(sl);
234 }
235 sl->rcount = 0;
236 } else {
237 if (!test_bit(SLF_ERROR, &sl->flags)) {
238 if (sl->rcount < SLC_MTU) {
239 sl->rbuff[sl->rcount++] = s;
240 return;
241 } else {
242 sl->dev->stats.rx_over_errors++;
243 set_bit(SLF_ERROR, &sl->flags);
244 }
245 }
246 }
247}
248
249 /************************************************************************
250 * STANDARD SLCAN ENCAPSULATION *
251 ************************************************************************/
252
253/* Encapsulate one can_frame and stuff into a TTY queue. */
254static void slc_encaps(struct slcan *sl, struct can_frame *cf)
255{
Andre Naujoks87397fe2013-09-13 19:37:13 +0200256 int actual, i;
257 unsigned char *pos;
258 unsigned char *endpos;
259 canid_t id = cf->can_id;
260
261 pos = sl->xbuff;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000262
263 if (cf->can_id & CAN_RTR_FLAG)
Andre Naujoks87397fe2013-09-13 19:37:13 +0200264 *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000265 else
Andre Naujoks87397fe2013-09-13 19:37:13 +0200266 *pos = 'T'; /* becomes 't' in standard frame format (SSF) */
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000267
Andre Naujoks87397fe2013-09-13 19:37:13 +0200268 /* determine number of chars for the CAN-identifier */
269 if (cf->can_id & CAN_EFF_FLAG) {
270 id &= CAN_EFF_MASK;
271 endpos = pos + SLC_EFF_ID_LEN;
272 } else {
273 *pos |= 0x20; /* convert R/T to lower case for SFF */
274 id &= CAN_SFF_MASK;
275 endpos = pos + SLC_SFF_ID_LEN;
276 }
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000277
Andre Naujoks87397fe2013-09-13 19:37:13 +0200278 /* build 3 (SFF) or 8 (EFF) digit CAN identifier */
279 pos++;
280 while (endpos >= pos) {
281 *endpos-- = hex_asc_upper[id & 0xf];
282 id >>= 4;
283 }
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000284
Andre Naujoks87397fe2013-09-13 19:37:13 +0200285 pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000286
Andre Naujoks87397fe2013-09-13 19:37:13 +0200287 *pos++ = cf->can_dlc + '0';
288
289 /* RTR frames may have a dlc > 0 but they never have any data bytes */
290 if (!(cf->can_id & CAN_RTR_FLAG)) {
291 for (i = 0; i < cf->can_dlc; i++)
292 pos = hex_byte_pack_upper(pos, cf->data[i]);
293 }
294
295 *pos++ = '\r';
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000296
297 /* Order of next two lines is *very* important.
298 * When we are sending a little amount of data,
299 * the transfer may be completed inside the ops->write()
300 * routine, because it's running with interrupts enabled.
301 * In this case we *never* got WRITE_WAKEUP event,
302 * if we did not request it before write operation.
303 * 14 Oct 1994 Dmitry Gorodchanin.
304 */
305 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
Andre Naujoks87397fe2013-09-13 19:37:13 +0200306 actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff);
307 sl->xleft = (pos - sl->xbuff) - actual;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000308 sl->xhead = sl->xbuff + actual;
309 sl->dev->stats.tx_bytes += cf->can_dlc;
310}
311
Tyler Halla8e83b12014-06-15 22:23:17 -0400312/* Write out any remaining transmit buffer. Scheduled when tty is writable */
313static void slcan_transmit(struct work_struct *work)
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000314{
Tyler Halla8e83b12014-06-15 22:23:17 -0400315 struct slcan *sl = container_of(work, struct slcan, tx_work);
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000316 int actual;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000317
Alexander Stein367525c2014-04-15 16:51:04 +0200318 spin_lock_bh(&sl->lock);
Tyler Halla8e83b12014-06-15 22:23:17 -0400319 /* First make sure we're connected. */
320 if (!sl->tty || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) {
321 spin_unlock_bh(&sl->lock);
322 return;
323 }
324
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000325 if (sl->xleft <= 0) {
326 /* Now serial buffer is almost free & we can start
327 * transmission of another packet */
328 sl->dev->stats.tx_packets++;
Tyler Halla8e83b12014-06-15 22:23:17 -0400329 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
Alexander Stein367525c2014-04-15 16:51:04 +0200330 spin_unlock_bh(&sl->lock);
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000331 netif_wake_queue(sl->dev);
332 return;
333 }
334
Tyler Halla8e83b12014-06-15 22:23:17 -0400335 actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft);
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000336 sl->xleft -= actual;
337 sl->xhead += actual;
Alexander Stein367525c2014-04-15 16:51:04 +0200338 spin_unlock_bh(&sl->lock);
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000339}
340
Tyler Halla8e83b12014-06-15 22:23:17 -0400341/*
342 * Called by the driver when there's room for more data.
343 * Schedule the transmit.
344 */
345static void slcan_write_wakeup(struct tty_struct *tty)
346{
347 struct slcan *sl = tty->disc_data;
348
349 schedule_work(&sl->tx_work);
350}
351
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000352/* Send a can_frame to a TTY queue. */
353static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
354{
355 struct slcan *sl = netdev_priv(dev);
356
357 if (skb->len != sizeof(struct can_frame))
358 goto out;
359
360 spin_lock(&sl->lock);
361 if (!netif_running(dev)) {
362 spin_unlock(&sl->lock);
363 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
364 goto out;
365 }
366 if (sl->tty == NULL) {
367 spin_unlock(&sl->lock);
368 goto out;
369 }
370
371 netif_stop_queue(sl->dev);
372 slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
373 spin_unlock(&sl->lock);
374
375out:
376 kfree_skb(skb);
377 return NETDEV_TX_OK;
378}
379
380
381/******************************************
382 * Routines looking at netdevice side.
383 ******************************************/
384
385/* Netdevice UP -> DOWN routine */
386static int slc_close(struct net_device *dev)
387{
388 struct slcan *sl = netdev_priv(dev);
389
390 spin_lock_bh(&sl->lock);
391 if (sl->tty) {
392 /* TTY discipline is running. */
393 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
394 }
395 netif_stop_queue(dev);
396 sl->rcount = 0;
397 sl->xleft = 0;
398 spin_unlock_bh(&sl->lock);
399
400 return 0;
401}
402
403/* Netdevice DOWN -> UP routine */
404static int slc_open(struct net_device *dev)
405{
406 struct slcan *sl = netdev_priv(dev);
407
408 if (sl->tty == NULL)
409 return -ENODEV;
410
411 sl->flags &= (1 << SLF_INUSE);
412 netif_start_queue(dev);
413 return 0;
414}
415
416/* Hook the destructor so we can free slcan devs at the right point in time */
417static void slc_free_netdev(struct net_device *dev)
418{
419 int i = dev->base_addr;
420 free_netdev(dev);
421 slcan_devs[i] = NULL;
422}
423
Oliver Hartkoppc971fa22014-03-07 09:23:41 +0100424static int slcan_change_mtu(struct net_device *dev, int new_mtu)
425{
426 return -EINVAL;
427}
428
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000429static const struct net_device_ops slc_netdev_ops = {
430 .ndo_open = slc_open,
431 .ndo_stop = slc_close,
432 .ndo_start_xmit = slc_xmit,
Oliver Hartkoppc971fa22014-03-07 09:23:41 +0100433 .ndo_change_mtu = slcan_change_mtu,
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000434};
435
436static void slc_setup(struct net_device *dev)
437{
438 dev->netdev_ops = &slc_netdev_ops;
439 dev->destructor = slc_free_netdev;
440
441 dev->hard_header_len = 0;
442 dev->addr_len = 0;
443 dev->tx_queue_len = 10;
444
445 dev->mtu = sizeof(struct can_frame);
446 dev->type = ARPHRD_CAN;
447
448 /* New-style flags. */
449 dev->flags = IFF_NOARP;
Michał Mirosław34324dc2011-11-15 15:29:55 +0000450 dev->features = NETIF_F_HW_CSUM;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000451}
452
453/******************************************
454 Routines looking at TTY side.
455 ******************************************/
456
457/*
458 * Handle the 'receiver data ready' interrupt.
459 * This function is called by the 'tty_io' module in the kernel when
460 * a block of SLCAN data has been received, which can now be decapsulated
461 * and sent on to some IP layer for further processing. This will not
462 * be re-entered while running but other ldisc functions may be called
463 * in parallel
464 */
465
Linus Torvalds55db4c62011-06-04 06:33:24 +0900466static void slcan_receive_buf(struct tty_struct *tty,
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000467 const unsigned char *cp, char *fp, int count)
468{
469 struct slcan *sl = (struct slcan *) tty->disc_data;
470
471 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
Linus Torvalds55db4c62011-06-04 06:33:24 +0900472 return;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000473
474 /* Read the characters out of the buffer */
Linus Torvalds55db4c62011-06-04 06:33:24 +0900475 while (count--) {
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000476 if (fp && *fp++) {
477 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
478 sl->dev->stats.rx_errors++;
479 cp++;
480 continue;
481 }
482 slcan_unesc(sl, *cp++);
483 }
484}
485
486/************************************
487 * slcan_open helper routines.
488 ************************************/
489
490/* Collect hanged up channels */
491static void slc_sync(void)
492{
493 int i;
494 struct net_device *dev;
495 struct slcan *sl;
496
497 for (i = 0; i < maxdev; i++) {
498 dev = slcan_devs[i];
499 if (dev == NULL)
500 break;
501
502 sl = netdev_priv(dev);
Matvejchikov Ilya7ad711b2011-07-18 21:58:48 +0000503 if (sl->tty)
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000504 continue;
505 if (dev->flags & IFF_UP)
506 dev_close(dev);
507 }
508}
509
510/* Find a free SLCAN channel, and link in this `tty' line. */
511static struct slcan *slc_alloc(dev_t line)
512{
513 int i;
Oliver Hartkopp2af4ba82011-07-14 21:49:19 +0000514 char name[IFNAMSIZ];
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000515 struct net_device *dev = NULL;
516 struct slcan *sl;
517
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000518 for (i = 0; i < maxdev; i++) {
519 dev = slcan_devs[i];
520 if (dev == NULL)
521 break;
522
523 }
524
525 /* Sorry, too many, all slots in use */
526 if (i >= maxdev)
527 return NULL;
528
Oliver Hartkopp2af4ba82011-07-14 21:49:19 +0000529 sprintf(name, "slcan%d", i);
Tom Gundersenc835a672014-07-14 16:37:24 +0200530 dev = alloc_netdev(sizeof(*sl), name, NET_NAME_UNKNOWN, slc_setup);
Oliver Hartkopp2af4ba82011-07-14 21:49:19 +0000531 if (!dev)
532 return NULL;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000533
Oliver Hartkopp2af4ba82011-07-14 21:49:19 +0000534 dev->base_addr = i;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000535 sl = netdev_priv(dev);
536
537 /* Initialize channel control data */
538 sl->magic = SLCAN_MAGIC;
539 sl->dev = dev;
540 spin_lock_init(&sl->lock);
Tyler Halla8e83b12014-06-15 22:23:17 -0400541 INIT_WORK(&sl->tx_work, slcan_transmit);
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000542 slcan_devs[i] = dev;
543
544 return sl;
545}
546
547/*
548 * Open the high-level part of the SLCAN channel.
549 * This function is called by the TTY module when the
550 * SLCAN line discipline is called for. Because we are
551 * sure the tty line exists, we only have to link it to
552 * a free SLCAN channel...
553 *
554 * Called in process context serialized from other ldisc calls.
555 */
556
557static int slcan_open(struct tty_struct *tty)
558{
559 struct slcan *sl;
560 int err;
561
562 if (!capable(CAP_NET_ADMIN))
563 return -EPERM;
564
565 if (tty->ops->write == NULL)
566 return -EOPNOTSUPP;
567
568 /* RTnetlink lock is misused here to serialize concurrent
569 opens of slcan channels. There are better ways, but it is
570 the simplest one.
571 */
572 rtnl_lock();
573
574 /* Collect hanged up channels. */
575 slc_sync();
576
577 sl = tty->disc_data;
578
579 err = -EEXIST;
580 /* First make sure we're not already connected. */
581 if (sl && sl->magic == SLCAN_MAGIC)
582 goto err_exit;
583
584 /* OK. Find a free SLCAN channel to use. */
585 err = -ENFILE;
586 sl = slc_alloc(tty_devnum(tty));
587 if (sl == NULL)
588 goto err_exit;
589
590 sl->tty = tty;
591 tty->disc_data = sl;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000592
593 if (!test_bit(SLF_INUSE, &sl->flags)) {
594 /* Perform the low-level SLCAN initialization. */
595 sl->rcount = 0;
596 sl->xleft = 0;
597
598 set_bit(SLF_INUSE, &sl->flags);
599
600 err = register_netdevice(sl->dev);
601 if (err)
602 goto err_free_chan;
603 }
604
605 /* Done. We have linked the TTY line to a channel. */
606 rtnl_unlock();
607 tty->receive_room = 65536; /* We don't flow control */
Oliver Hartkopp0d4420a2011-05-10 13:12:30 -0700608
609 /* TTY layer expects 0 on success */
610 return 0;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000611
612err_free_chan:
613 sl->tty = NULL;
614 tty->disc_data = NULL;
615 clear_bit(SLF_INUSE, &sl->flags);
616
617err_exit:
618 rtnl_unlock();
619
620 /* Count references from TTY module */
621 return err;
622}
623
624/*
625 * Close down a SLCAN channel.
626 * This means flushing out any pending queues, and then returning. This
627 * call is serialized against other ldisc functions.
628 *
629 * We also use this method for a hangup event.
630 */
631
632static void slcan_close(struct tty_struct *tty)
633{
634 struct slcan *sl = (struct slcan *) tty->disc_data;
635
636 /* First make sure we're connected. */
637 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
638 return;
639
Tyler Halla8e83b12014-06-15 22:23:17 -0400640 spin_lock_bh(&sl->lock);
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000641 tty->disc_data = NULL;
642 sl->tty = NULL;
Tyler Halla8e83b12014-06-15 22:23:17 -0400643 spin_unlock_bh(&sl->lock);
644
645 flush_work(&sl->tx_work);
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000646
647 /* Flush network side */
648 unregister_netdev(sl->dev);
649 /* This will complete via sl_free_netdev */
650}
651
652static int slcan_hangup(struct tty_struct *tty)
653{
654 slcan_close(tty);
655 return 0;
656}
657
658/* Perform I/O control on an active SLCAN channel. */
659static int slcan_ioctl(struct tty_struct *tty, struct file *file,
660 unsigned int cmd, unsigned long arg)
661{
662 struct slcan *sl = (struct slcan *) tty->disc_data;
663 unsigned int tmp;
664
665 /* First make sure we're connected. */
666 if (!sl || sl->magic != SLCAN_MAGIC)
667 return -EINVAL;
668
669 switch (cmd) {
670 case SIOCGIFNAME:
671 tmp = strlen(sl->dev->name) + 1;
672 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
673 return -EFAULT;
674 return 0;
675
676 case SIOCSIFHWADDR:
677 return -EINVAL;
678
679 default:
680 return tty_mode_ioctl(tty, file, cmd, arg);
681 }
682}
683
684static struct tty_ldisc_ops slc_ldisc = {
685 .owner = THIS_MODULE,
686 .magic = TTY_LDISC_MAGIC,
687 .name = "slcan",
688 .open = slcan_open,
689 .close = slcan_close,
690 .hangup = slcan_hangup,
691 .ioctl = slcan_ioctl,
692 .receive_buf = slcan_receive_buf,
693 .write_wakeup = slcan_write_wakeup,
694};
695
696static int __init slcan_init(void)
697{
698 int status;
699
700 if (maxdev < 4)
701 maxdev = 4; /* Sanity */
702
Jeremiah Mahlerace9bb22014-12-03 00:44:04 -0800703 pr_info("slcan: serial line CAN interface driver\n");
704 pr_info("slcan: %d dynamic interface channels.\n", maxdev);
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000705
706 slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
Joe Perchese404dec2012-01-29 12:56:23 +0000707 if (!slcan_devs)
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000708 return -ENOMEM;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000709
710 /* Fill in our line protocol discipline, and register it */
711 status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
712 if (status) {
713 printk(KERN_ERR "slcan: can't register line discipline\n");
714 kfree(slcan_devs);
715 }
716 return status;
717}
718
719static void __exit slcan_exit(void)
720{
721 int i;
722 struct net_device *dev;
723 struct slcan *sl;
724 unsigned long timeout = jiffies + HZ;
725 int busy = 0;
726
727 if (slcan_devs == NULL)
728 return;
729
730 /* First of all: check for active disciplines and hangup them.
731 */
732 do {
733 if (busy)
734 msleep_interruptible(100);
735
736 busy = 0;
737 for (i = 0; i < maxdev; i++) {
738 dev = slcan_devs[i];
739 if (!dev)
740 continue;
741 sl = netdev_priv(dev);
742 spin_lock_bh(&sl->lock);
743 if (sl->tty) {
744 busy++;
745 tty_hangup(sl->tty);
746 }
747 spin_unlock_bh(&sl->lock);
748 }
749 } while (busy && time_before(jiffies, timeout));
750
751 /* FIXME: hangup is async so we should wait when doing this second
752 phase */
753
754 for (i = 0; i < maxdev; i++) {
755 dev = slcan_devs[i];
756 if (!dev)
757 continue;
758 slcan_devs[i] = NULL;
759
760 sl = netdev_priv(dev);
761 if (sl->tty) {
762 printk(KERN_ERR "%s: tty discipline still running\n",
763 dev->name);
764 /* Intentionally leak the control block. */
765 dev->destructor = NULL;
766 }
767
768 unregister_netdev(dev);
769 }
770
771 kfree(slcan_devs);
772 slcan_devs = NULL;
773
774 i = tty_unregister_ldisc(N_SLCAN);
775 if (i)
776 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
777}
778
779module_init(slcan_init);
780module_exit(slcan_exit);